The invention relates to a device for current sensing in an amplifier with PMOS (Positive channel Metal Oxide Semiconductor) voltage conversion. More specifically, the invention relates to a device that may quickly convert a current detected to a voltage that may be used for processing purposes in a microprocessor.
In the rapid development of computers many advancements have been seen in the areas of processor speed, throughput, communications, and fault tolerance. Microprocessor speed is measured in cycles per second or hertz. Today""s high-end 32-bit microprocessors operate well in excess of 1 Ghz (gigahertz), one billion cycles per second, and in the near future this is expected to go substantially higher. At this sort of cycle speed a clock would have to generate a pulse or cycle at least once each billionth of a second and usually several orders of magnitude faster. It is during this clock cycle that the processor executes programmed functions. These functions would include everything from a portion of a read function to some mathematical operation. Further, complexity of the operation performed by a microprocessor has increased exponentially. Today, a microprocessor is expected to perform mathematical operations on 32, 64, and a 128 bit words. Further, in microprocessor chips not only are mathematical as well as logical functions performed but memory related functions take plage sugh as the management of cache memory. With the increase in the complexity of the functions performed the lengths in data paths and logic paths required has also increased. This increase in data and logic paths length has served to slow processor execution. This is because the fundamental mechanism used to communicate between components is through resistance/capacitance (RC) networks which are inherently slow. The longer the distance of the logic path the more R/C networks involved and the slower the processor. Thus, the need to increase speed is at odds with the need to increase complexity.
The reason for this conflict lies within the fundamental mechanism by which components in a processor on a single chip exchange information. The fundamental mechanism by which data processors operate is through the representation of logical states in data as binary values (either zero or one). At the hardware level a binary value of one may be represented by high or positive voltage or current, while a binary value of zero may be represented by a low or negative voltage or current. Presently a transmitting circuit would set a voltage high and that would be transmitted to a receiving circuit. The receiving circuit would determine or sense the signal, referred to as voltage sensing, and take the appropriate action.
An alternative approach would utilize current sensing rather than voltage sensing and this is often called a differential current system and the receiving or detecting circuit would be called a current conveyer. This current conveyer has almost zero input resistance at the leading end and thus the current conveyer can detect, almost instantaneously, the presence of current. However, all computations and logic in the microprocessor are still based on voltage rather than current. Therefore, current must then be converted back to voltage and the current mechanisms, prior to the present invention, used to convert from current to voltage are relatively slow because it was more complex requiring more devices, that took up more space on the chip and used more power which required more cooling. Thus, a potential limit, block or envelope exists that may prevent the further increase in microprocessor speed and complexity to one, two, three, or more gigahertz per second.
Therefore, what is needed is a device that will take advantage of the near instantaneous detection of a change in current realized by a current conveyer but will almost as quickly be able to convert this detected current back to a voltage. This device should be simple to implement and thereby be able to operate quickly. Further, it must take up as little space on the microprocessor chip so that the space may be utilized for logic, mathematical functions as well as expanded cache memory.